Abrasive tool for a sanding machine

Abstract

The present invention relates to an abrasive tool for a sanding machine comprising a disc-shaped body and a plurality of abrasive strips, each removably engaging said body, the body further comprising a plurality of support elements for the abrasive strips, said support elements protruding from a working face of the body, wherein the support element comprises a support surface, facing a rear face of each abrasive strip, said support surface being formed on a front wall of the support element arranged substantially radial with respect to the axis of the body, wherein said front wall comprises at least one concave section, with the concavity facing the working face of the body.

Description

[0001] TITLE

[0002] ABRASIVE TOOL FOR SANDING MACHINE

[0003] DESCRIPTION

[0004] The present invention relates to an abrasive tool for carrying out work on flat surfaces, in particular floors. More specifically, the tool of the present invention may be used to perform sanding or polishing operations on flat surfaces of various materials such as composite materials, resins, wood, paints, concrete or stone materials.

[0005] The tool of the present invention is intended to be mounted on semi-portable floor sanding machines, such as planetary or roto-planetary type, configured to accommodate three, four or more abrasive tools.

[0006] To carry out the above-mentioned sanding and / or polishing processes on floors or other equivalent flat surfaces, depending on the material of the surface to be treated, two types of sanding machines are generally used: belt or roller sanders or disc sanders. The latter may be equipped with a single rotating disc / tool (so-called single-disc or single-brush sanders) or with multiple discs / tools (so-called planetary or roto-planetary sanders) which are rotated around their own axis and at the same time around a circumferential trajectory.

[0007] The tool of the present invention is particularly suitable for use with the above- mentioned planetary or single-disc sanders, and may equally be used with portable sanding machines, so-called “palmtops”.

[0008] For this type of machine, various abrasive tools are known with different shapes and configurations and provided with abrasive elements of various materials.

[0009] A particularly common type of tool consists of a support disc with a substantially flat work surface on which a disc of abrasive paper or cloth is removably fixed.

[0010] This type of tool, although very versatile and relatively inexpensive, has some limitations.

[0011] A first drawback that affects these flat abrasive discs (also called “pads” in jargon) is the rapid wear to which they are subject, especially when working on hard and resistant materials. This rapid wear involves a considerable waste of time and frequent interruptions in processing to replace the abrasive elements.

[0012] Furthermore, given the extension of the abrasive surface, it is difficult to guarantee a uniform and constant contact pressure for all tools and in all areas of the treated surface. This circumstance may generate unwanted or aesthetically unacceptable traces of processing (the so-called “swirls”), on the treated surface.

[0013] Another type of well-known and rather widespread abrasive tool consists of a support disc on the lower face of which are applied rigid protruding inserts, integral with the disc and removable, each having at least one working surface coated with an abrasive material, for example diamond-based. Such a known tool is described for example in US6454644B 1.

[0014] Such tools are generally intended for use with hard materials such as concrete, stone and the like. A drawback of these tools is that, being usually substantially non-deformable, they are not able to adapt to any irregularities in the surface to be treated. This circumstance may lengthen the processing times to ensure that the entire surface (ridges and valleys) are worked. Furthermore, these types of tools transmit significant vibrations to the sanding machine, making the operation more tiring for the operator.

[0015] Also known in the sector are abrasive discs for sanders comprising a circular support whose lower face is provided with a plurality of bracket-type fixing elements, generally made of metal, to which slats made of abrasive paper or cloth are fixed.

[0016] Examples of such tools are described for example in W02008088908A1 and WO2022251798A1.

[0017] These tools are also subject to premature wear due to the reduced number of abrasive elements that may be installed (due to the size of the fixing bracket) on which the entire weight of the sanding machine is discharged (even up to 70 kg). WO2005113198A2 describes a tool for smoothing concrete surfaces which comprises a disc-shaped support and a plurality of abrasive elements in the form of strips fixed to the support. The abrasive elements are arranged radially with respect to the rotation axis of the support and are fixed thereto in a removable manner for replacement. The abrasive elements are made of metal and are coated with an abrasive material.

[0018] EP1633530A1 describes an abrasive tool similar to the previous one, in which the abrasive elements comprise strips of abrasive cloth associated with support bristles placed close to the rear, non-working face of the abrasive cloth. Such bristles give greater rigidity to the abrasive cloth, optimising the curvature profile thereof when pressed on the surface to be treated. An example of such an abrasive element is also described in W02011110176A1.

[0019] Such tools, however, offer good performance when used with portable sanders or, in any case, with smaller weight and dimensions.

[0020] In fact, despite the presence of support bristles, these abrasive elements may withstand a limited axial load, i.e. normal to the surface to be treated.

[0021] The weight of a semi-portable floor sander, which, as mentioned above, may reach up to 70 kg, would cause excessive bending of the abrasive cloth (crushing) which would not allow it to work correctly.

[0022] In this context, the object of the present invention is therefore to propose an abrasive tool for sanding machines that allows overcoming the above-mentioned drawbacks that affect the tools of the prior art.

[0023] In detail, the object of the present invention is to propose an abrasive tool which allows for the efficient management of the contact pressure of the abrasive elements with the surface to be treated.

[0024] In particular, the object of the present invention is to provide an abrasive tool which guarantees consistent processing quality on surfaces of various types and with sanding machines of different sizes.

[0025] Another object of the present invention is to propose a tool which guarantees a longer life and which, therefore, does not require frequent interruptions and machine downtime to carry out maintenance and repair operations.

[0026] Another object of the present invention is to propose a versatile abrasive tool which may be used for different operations on various surfaces.

[0027] These and other objects are achieved by an abrasive tool for sanding machines, in particular sanders for a flat surface such as a floor or the like, according to the appended claim 1.

[0028] In detail, according to the present invention, the abrasive tool comprises a discshaped body with a first working face which, in use, faces the surface to be treated, and a second opposite face, provided with connection means for connecting the abrasive tool to the sanding machine.

[0029] Said connection means are of a known type and will therefore not be described in detail.

[0030] A plurality of slots is obtained on the said working face of the body.

[0031] The tool further comprises a plurality of abrasive strips, each removably engaging one of the slots. Each strip includes at least one attachment portion, held in said slot, and a flexible working portion, with at least one front abrasive face.

[0032] Said front abrasive face of the working portion is coated with an abrasive material, for example abrasive particles dispersed in a binding material.

[0033] According to the invention, said abrasive strips are mounted on said body in such a way that the front abrasive face is aligned substantially transverse to the motion direction of the body. Typically, said abrasive strips are arranged substantially radial with respect to the axis of the body.

[0034] The body, according to the invention, is provided with a plurality of support elements for the working portion of the abrasive strips. Said support elements protrude from the working face of the body and are arranged between two adjacent and consecutive slots.

[0035] Said support elements have the task of limiting the bending and crushing of the abrasive strips due to the weight of the sanding machine which mainly bears on the abrasive strips.

[0036] For this purpose, according to the invention, each support element comprises a support surface, facing a rear face of each abrasive strip.

[0037] When the sanding machine is in operating condition, its weight is discharged onto the rotating support on which one or more abrasive tools are mounted. This condition causes the abrasive strips to be crushed, which, by virtue of the direction of motion of the body (rotation or roto-translation), deform, bringing their rear face at least partially into contact with said support surface of the support element.

[0038] Advantageously, according to the present invention, said support surface is obtained on a front wall of the support element arranged substantially radial with respect to the axis of the body, where said front wall comprises at least one concave section, with the concavity facing the working face of the body.

[0039] Such conformation of the support surface ensures that the pressure created during processing between the front abrasive face of the working portion and the surface to be treated is distributed evenly over the entire front abrasive face.

[0040] Such condition brings more advantages. First, the front abrasive face is subjected to even wear which maximizes the life of the abrasive strip.

[0041] Furthermore, the deformed profile that the abrasive strip assumes during processing allows for an increase in the effective working surface, significantly reducing processing times.

[0042] Furthermore, by virtue of the aforementioned conformation of the support elements, the various abrasive strips of the tool may work with very similar contact pressure values, ensuring a better surface finish.

[0043] According to one aspect of the invention, said front wall extends from the working face of the body to an end edge distal from said working face. Preferably, said end edge of the front wall coincides with the terminal edge of the concave section. Said end edge is preferably straight.

[0044] According to another aspect of the invention, the front wall includes a first section which is substantially flat and arranged orthogonal to the working face of the body, and a second concave section which extends to the end edge.

[0045] According to one aspect of the invention, the support element further comprises a reinforcing element, which extends from the working face of the body to said end edge of the front wall. Said reinforcing element preferably consists of a rear wall, typically flat, of the support element.

[0046] Overall, the front and rear walls of the support element define an elongated and hollow element, with a substantially asymmetrical arched profile.

[0047] Such conformation allows for the creation of a plurality of ducts through which the debris and processing residues of the treated surface may be conveyed and laterally expelled.

[0048] According to one aspect of the invention, the external lateral edge of the support element is arranged at the peripheral edge of the body. The extension (length) of the support element along a radial direction of the body is preferably between 1 / 3 and 2 / 3 of the value of the body radius. Such value is generally at least equal to or preferably less than the length of the abrasive strip.

[0049] According to another aspect of the invention, the support element has an extension in height, i.e. in a direction normal to the working face of the body, increasing from the center of the body towards the peripheral edge.

[0050] Such conformation allows for greater support to be provided to the abrasive strip in the peripheral area of the body where it is subject to greater stresses and loads than the internal area.

[0051] According to another aspect of the invention, the support element has an extension in width increasing towards the external peripheral edge of the body.

[0052] Also, in this case, such conformation of the support element allows for greater support of the external part of the abrasive strip which works at higher peripheral speeds than the internal part.

[0053] According to another aspect of the invention, said support elements may be made integrated with the body or may be removable. In the second case, the body and the support elements are equipped with respective connecting or coupling means, such as screws, interlocking means, snap-fit means, or equivalent.

[0054] In this way, it is possible to replace the support elements both in case they are worn or damaged, and to be able to vary the dimensions and geometry thereof, depending on both the features of the abrasive strips used and the material of the surface to be treated.

[0055] Furthermore, according to this variant, it is also possible to vary the material of the support elements by choosing more or less rigid / deformable materials, always depending on the features of the abrasive strips used and the material of the surface to be treated.

[0056] According to another aspect of the invention, a plurality of radially arranged blades is obtained in the central area of the body to form an impeller. Said impeller is adapted to generate a radial air flow which both facilitates the expulsion of debris and processing residues and cools the abrasive strips.

[0057] Further features and advantages will become apparent in the indicative, and therefore non-limiting, description of an example of a preferred, but non-exclusive, embodiment of the invention, as illustrated in the accompanying figures in which:

[0058] - Figure 1 is a top perspective view of the abrasive tool according to the present invention; - Figure 2 is a perspective bottom view of the tool of Figure 1 ;

[0059] - Figure 3 is a lateral view of the tool of Figure 1 ;

[0060] - Figure 4 is a perspective top view of the body of the tool of Figure 1 ;

[0061] - Figure 5 is a sectional view of the body of the tool of Figure 1 along a plane A-A parallel to the body axis.

[0062] With reference to the accompanying figures, the reference numeral 1 indicates as a whole the abrasive tool according to a preferred embodiment of the present invention.

[0063] The tool 1 comprises a body 10 of flattened and circular shape with a first face 12, here also defined as the working face, and a second opposite face 11.

[0064] The body has a diameter generally between 100 mm and 430 mm, preferably between 120 mm and 200 mm.

[0065] On the second face 11, which in use faces towards the sanding machine, i.e. upwards if it is a floor sander, connection means 13 are provided for connecting the tool to the drive plate of the machine, directly or through the interposition of further components. Such connection means are known to those skilled in the art and will therefore not be described in detail.

[0066] On the working face 12, which in use faces the surface to be treated, a plurality of slots 15 or grooves are obtained, arranged radially with respect to the center of the body 10.

[0067] Each slot 15 defines a seat 16 which may accommodate a portion of an abrasive strip, generally indicated with 30.

[0068] In the example illustrated, all slots 15 accommodate an abrasive strip 30. However, depending on the type of machining to be carried out, the material of the surface to be treated and the features of the abrasive strip 30, the tool 1 may be used with a lower number of abrasive strips 30 than the slots.

[0069] According to a preferred embodiment, the abrasive strip 30 comprises an attachment portion 31 which is slidably housed in the seat 16 of the slot 15. Such attachment portion 31 has a profile complementary to the profile of the seat 16, for example dovetailed, as in the example illustrated, which allows the abrasive strip 30 to be blocked in the seat 16. As previously mentioned, the abrasive strip 30 engages the slot 15 in a removable manner, being able to slide inside it, along a radial direction. Preferably, the coupling between the attachment portion 31 of the abrasive strip and the walls of the seat 16 is achieved with minimal clearance, so that the abrasive strip may be inserted and removed easily. Preferably, retaining means 17 are arranged at the peripheral edge 14 of the body 10 to prevent the abrasive strips 30 from coming out of the seat during processing due to the centrifugal force. Said retaining means 17 comprise for example an annular element which partially or completely covers the lateral ends of the slots 15 in which the abrasive strips can slide.

[0070] The abrasive strip 30 further comprises a central portion 32, which extends from the attachment portion 31 and generally protrudes from the slot 15, and a working portion 33, which extends as a continuation of the central portion 32, which terminates with an end edge 34.

[0071] The central portion 32 and the working portion 33 are typically made from a single piece of the same material, such as a flexible canvas or paper support.

[0072] The working portion 33, on a front face 35a of the abrasive strip 30, is coated with an abrasive material, generally comprising abrasive particles, for example diamond-based or synthetic abrasives, dispersed in a binding material that allows the particles to remain adhered to the surface of the abrasive strip 30.

[0073] In a preferred embodiment, the abrasive strip 30 further comprises bristles 36 extending from the attachment portion 31 toward the end edge 34 of the working portion 33, which are arranged adjacent to a rear face 35b of the abrasive strip 30. Such bristles 36 have the task of limiting the bending of the abrasive strip 30 during processing. An example of a flexible strip 30 with such features is described in

[0074] W02011110176A1.

[0075] The length of the abrasive strips 30, i.e. the extension thereof in the radial direction, is between 2 / 3 and 5 / 6 of the length of the radius of the body 10.

[0076] The height of the abrasive strips 30, i.e. the extension of the central portion 32 and working portion 33 up to the end edge 34, is generally between 20 mm and 60 mm, preferably between 30 mm and 50 mm. Such value may vary depending on the material of the abrasive strip, its length (therefore the dimensions of the body 10) and the type of processing / application for which the abrasive strip is designed.

[0077] According to the invention, a plurality of support elements 40 is provided on the working face 12 of the body 10. In the illustrated example, such support elements 40 are made integral with the body 10.

[0078] Suitable materials for the construction of the body 10 are, for example, thermoplastic polymers (polyamide, polyethylene, polypropylene, etc.), possibly reinforced with fibers, or metals, for example aluminium.

[0079] However, the use of materials with greater elasticity, such as elastomers, is not excluded.

[0080] Said support elements 40 protrude from the working face 12 and are arranged alternating with the slots 15. In practice, each support element 40 is arranged between two slots 15 and each slot 15 is arranged between two support elements 40.

[0081] Each support element 40 has an elongated, hollow shape and is arranged radially aligned with respect to the center of the body 10.

[0082] In the illustrated example, the support element 40 comprises a front wall 41 which has a support surface 42 facing the rear face 35b of an adjacent abrasive strip 30.

[0083] Said front wall 41 has a first flat section 41a which extends orthogonally to the working face 12 and a second concave section 41b, with the concavity facing the working face 12, which extends between an initial edge 43 and an end edge 44.

[0084] In the illustrated example, said second concave section 41b of the front wall 41 has a truncated cone sector-like extension, i.e. where the initial edge 43 and the end edge 44 represent the apothem rotated around an axis of rotation by an angle preferably between 45° and 90°. More precisely, the base of the said truncated cone sector wall faces outwards.

[0085] Such configuration of the support element 40, in particular of the truncated cone sector extension of the concave section 41b, means that said support element has an extension in height and width which increases from the center of the body 10 towards its peripheral edge 14.

[0086] The support element 40 further comprises a rear wall 45, which acts as a reinforcement element or the front wall, which extends orthogonally from the working face 12 of the body 10 to the end edge.

[0087] Between said front 41 and rear parts 45 and the working face 12 of the body 10 a duct 47 is defined with a section increasing towards the peripheral edge 14 of the body 10.

[0088] The extension of the support element 40 along a radial direction of the body 10 is generally between 1 / 3 and 2 / 3 of the length of the radius of the body 10.

[0089] In the example illustrated, in the central area of the body 10 there are a plurality of blades 51, preferably made integral with the body 10. The blades 51, which extend orthogonally to the working face 12, have a curved plan profile, overall forming an impeller 50 with curved blades. The trailing edge 51a of the blades 51 is located in proximity to an internal edge 47 of the support elements. In this way, the flow of air expelled by said blades is conveyed partly onto the flexible abrasive strips and partly inside the ducts 47 formed by each support element 40.

[0090] The present invention thus described and illustrated is subject to numerous modifications and variants, all falling within the scope of the inventive concept; moreover, all details may be replaced by other technically equivalent elements.

Claims

CLAIMS1. An abrasive tool (1) for a sanding machine, in particular a sander for a flat surface such as a floor or the like, comprising: a body (10) of a circular and flattened shape with a first working face (12) which, in use, faces the surface to be treated, and a second opposite face (11), provided with connection means (13) to connect the tool (1) to the sanding machine, said body (10) comprising a plurality of slots (15) obtained on said working face (12); a plurality of abrasive strips (30) each removably engaging one of the slots (15), each abrasive strip (30) including at least one attachment portion (31), held in the slot (15), and a flexible working portion (33), with at least one front abrasive face (35a), said abrasive strips (30) being mounted on said body (10) in such a way that the front abrasive face (35a) is arranged substantially transverse to the motion direction of the body (10); wherein the body (10) is provided with a plurality of support elements (40) of the abrasive strips (30), said support elements protruding from the working face (12) and being arranged between two side-by-side slots (15), characterized in that the support element (40) includes a support surface (42), facing a rear face (35b) of an abrasive strip (30), said support surface (42) being formed on a front wall (41) of the support element (40) arranged substantially radial with respect to the axis of the body (10), where said front wall (41) includes at least one concave section (41b), with the concavity facing the working face (12) of the body (10).

2. The tool (1) according to claim 1, wherein said front wall (41) extends from the working face (12) of the body (10) up to an end edge (44), distal from said working face, said end edge (44) coinciding with a terminal edge of the concave section (41b).

3. The tool (1) according to claim 2, wherein said end edge (44) is straight.

4. The tool (1) according to claim 2 or 3, wherein the front wall (41) includes a firstsection (41a) which is substantially flat and arranged orthogonal to the working face (12) of the body (10), and a second concave section (41b) which extends to the end edge (44).

5. The tool (1) according to claim 2, wherein the support element (40) includes a reinforcing element (45) which extends between the working face (12) of the body (10) and said end edge (44) of the front wall (41).

6. The tool (1) according to any one of the preceding claims, wherein an external lateral edge of the support element (40) is arranged at a peripheral edge (14) of the body (10), said support element (40) having an extension in length between 1 / 3 and 2 / 3 of the value of the radius of the body (10).

7. The tool (1) according to any one of the preceding claims, wherein the support element (40) has an extension in height increasing from the center towards a peripheral edge (14) of the body (10).

8. The tool (1) according to any one of the preceding claims, wherein the support element (40) has an extension in width increasing from the center towards a peripheral edge (14) of the body (10).

9. The tool (1) according to any one of the preceding claims, wherein said support elements (40) are connected to the body (10) via removable connection means.

10. The tool (1) according to any one of the preceding claims, wherein in the central area of the body (10), on the side of the working face (12), a plurality of blades (51) are obtained, arranged radially to form an impeller (50).

Images